Hillary Clinton leaves her job Friday as secretary of state with sky-high approval ratings, and there's already a superPAC established urging her to run for president in 2016.

She's one of the most famous women in the world and, as she leaves office, perhaps the most popular politician in the country.

"And I would argue, the most formidable, with the possible exception of President Obama," says Dee Dee Myers, former White House press secretary for Clinton's husband, President Bill Clinton.

It's hard to remember that just four years ago, Clinton was rejected by her own party as its presidential candidate at a time when her approval rating was somewhere in the mid-40s.

There's no question that being out of politics for four years has enhanced her political reputation.

"The way she got there was just by doing the hard work," says Myers. "She focused on the task at hand. And people came along."

She's won universal praise, even though she leaves behind no Clinton peace treaty or Clinton arms accords. She's also been the subject of gushing tributes, including an affectionate appearance on CBS' 60 Minutes with her former rival and current boss — President Obama — who thanked Clinton for her service.

"I think Hillary will go down as one of the finest secretary of states we've had," Obama said. "It has been a great collaboration over the last four years."

Comfortable In The Hot Seat

At the tail end of her tenure, there was a display of one of Clinton's career trademarks: sitting on the hot seat. This time it was congressional hearings about the attack on the U.S. Consulate in Benghazi, Libya.

Clinton suffered not a scratch, even during a tense exchange with Sen. Ron Johnson, R-Wis., who accused government officials of providing misleading information about the events that led up to the September attacks that killed Ambassador Chris Stevens and three other Americans.

"With all due respect, the fact is we had four dead Americans," Clinton responded. "Was it because of a protest or was it because of guys out for a walk one night who decided they'd go kill some Americans? What difference, at this point, does it make?"

Johnson followed a long line of men who have come out on the wrong end of a tangle with Clinton, including Obama, who told her she was "likable enough" during a 2008 debate, and lived to regret it.

After the exchange at the Benghazi hearings, Johnson gave an interview where he suggested Clinton had used emotion to duck the tough questions. Then Johnson had to backtrack in a later interview with CNN's Soledad O'Brien.

All that just reinforces the notion that Clinton, who has taken so much incoming fire over her career, is now fireproof.

"One of the things that's benefited her is just years of experience, being in the trenches day after day," says Myers. "She's not intimidated by a senator from Wisconsin, right? That to her is just another day at the office. What I think was most impressive about her performance was that she was ultimately and totally in control of what she said and didn't say and how she played it. She controls the tempo of the game now in any room that she's in, and it's an impressive thing to observe."

2016 Speculation

If Clinton does decide to run for president in four years, and the speculation about that is everywhere, she would be 69 by Election Day. But maybe the first female nominee has to be older in order to accumulate the kind of resume that would shut down any questions about whether she is qualified.

"She is [a] more admired, less polarizing figure than she was in 2008," says Democratic strategist Geoff Garin, who has worked for Clinton in the past. "The political prospects are really quite good, and better than they were when she last ran for president."

Other Democrats say she'd be a field-clearing front-runner. It's hard to imagine any Democrat on the scene today who could beat her in a primary. Of course not even her closest friends know what she will decide to do.

Myers has this theory:

"One of the things I think that Hillary has done consistently over the course of her career is she's always opted for institutional power. She wants to make big change, touch people's lives in a lasting way. Now she faces a similar decision. She can join her husband's foundation. She can create her own foundation. She can work on issues she cares deeply about and have a huge impact, but it's not the kind of institutional power that she seems to gravitate toward."

As for Clinton herself, she hasn't ruled anything out. She talked about her future with NPR's Michele Kelemen earlier this week:

"I don't see myself getting back into politics. I want to be involved in philanthropy, advocacy, working on issues like women and girls that I care deeply about. I want to write and speak. I want to work with my husband and my daughter on our mutual foundation interests. So I'm going to have my hands full. I don't quite know how I'm going to adjust to not having a schedule."

She also says she wants to catch up on 20 years of sleep deprivation. But sooner or later, one of the nation's most popular politicians will have to make a choice, whether or not to run for president.